Fluoroxidants

ABSTRACT

1. A compound of the formula WHEREIN Q is an atom in its highest oxidation state, said atom being selected from the class consisting of carbon and phosphorus, Rf is selected from the class consisting of fluorine and perfluoroalkyl radicals, m is 1-5 and n is zero to 2; and when Q is carbon and n is zero, Rf is perfluoroalkyl and includes Q. 2. Trifluoromethyl peroxyfluoride having the formula

United States Patent Thompson [451 Sept. 19, 1972 [54] FLUOROXIDANTS [72] Inventor: Phillip G.

Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, Saint Paul, Minn.

221 Filed: Jan. 20, 1964 211 App]. No.: 339,026

Thompson, St. Paul,

[52] US. Cl ..260/453 R, 23/ 165, 23/ 166, 23/203, 204/l57.l R, 204/158 R, 260/297 R,

260/502 R, 260/610 R, 260/610 D [51] Int. Cl. ..C07c 71/00, C076 73/00 [58] Field of Search...260/544 F, 502 R, 297 R, 545, 260/610 R, 610 D; 23/165, 203, 166

[56] References Cited OTHER PUBLICATIONS Lang s Handbook of Chemistry, 6th Edition, 1946, page 262 (TP 151 H25) Gatti et al. Angew. Chem, Vol. 75, No. 2 p. 137 Jan. 21, 1963 OD 125 Primary Examiner-Leland A. Sebastian Attorney-Frank A. Steldt and Donald C. Gipple EXEMPLARY CLAIM l. A compound of the formula 2. Trifluoromethyl peroxyfluoride having the formula CF OOF.

3 Claims, No Drawings FLUOROXIDANTS This invention relates to certain fiuorinated oxidant compounds and more particularly to certain novel peroxyfluorides.

The compounds of the invention are not, so far as applicant is aware, related to any class of heretofore known compounds.

The compounds of the invention are oxidizing agents and are useful for the purpose of bleaching, organic synthesis and the like. They are especially advantageous in that they have unique compatibility with systems in which perfluorinated solvents are used or perfluorinated compounds are treated. The compounds, when of lower molecular weight, as, for example, containing alkyl radicals having from one to four carbon atoms, are gases; when the alkyl radicals contained in the compounds are of higher molecular weight, the compounds are liquids. They are soluble in fluorinated compounds, such as chlorofluorocarbons (including CFCl and CF Cl fluorocarbons (including C l and perfluorobenzene) etc.

The compounds of the invention contain the moiety OOF joined to the remainder of the compound through an atom of the group consisting of carbon, sulfur and phosphorus, the said atom being in its highest valence state; and the remainder of the compound consisting of a non-metallic radical which is free from groups which are reducing in the respect to the OOF group and when carbon is present, at least one substituent fluorine atom is attached thereto. More specifically, and illustrative of a group of preferred compounds, the compounds can be represented by the formula wherein Q is an atom in its highest oxidation state, said a'tom being selected from the group consisting of carbon, sulfur and phosphorus, R, is selected from the group consisting of fluorine and perfluoroalkyl radicals, m is -5 and n is O-2.

Exemplary compounds of the invention are:

It is noted that compounds containing two or more OOF groups can also be prepared.

In the examples set forth above, R, can be a perfluoroalkyl radical having up to about 18 carbon atoms. Fully equivalent with acyclic fluoroalkyl radicals for the purpose of the invention are perfluoroalkyl radicals containing perfluorinated carbocyclic and heterocyclic rings, for example, perfluoropyridyl, perfluorocyclohexyl, perfluorocyclohexylethyl and the like radicals. Likewise, the perfluoroalkyl radicals can be substituted by certain electronegative groups, which may replace one or more fluorine atom or CE, groups. They are characterized by being free from hydrogen and having a Hammett meta sigma parameter equal to or greater than 0.3. (reference is here made to the report of H. H. .laffe, Chemical Reviews, Vol53, pp. l9l-26l 1953). Such groups include oxidizing groups such as NF NF, NO2, chlorine, bromine and the like groups. These substituents do not interfere with the fluorination of the starting compound, and contribute significant additional oxidizing power to the compounds of the invention. Perfluoroalkyl radicals thus substituted are included within the scope of R, as above defined.

The compounds of the invention can be prepared in general by the reaction of an acid, an acid anhydride, or a salt of an acid or a peroxide with fluorine or a fluoroxy compound. In many cases the acid salt is preferred over the acid or the anhydride.

Salts which can be employed in the fluorination process are, for example, the alkali metal salts, other metal salts, or ammonium salts of polyhaloalkanoic acids, which are exemplified by the acids having the formulae:

X(CF2),,COOH

R,OCF2CF2COOH z-crcucn-crcn cr coon Z-(CF -CFCI),,CF COOH and CF ClCF (CFClCF CFClCOOH wherein X is a member of the group consisting of chlorine and fluorine; Z is a perhalomethyl radical having a total atomic weight not greater than 146.5; R, is a perfluoroalkyl radical having from one to eight carbon atoms; n is an integer from I to 12; and m is a number from 0 to 5.

Other salts which may be employed are those of such acids as 0 l (C F): OH

Acid anhydrides which may be employed in reactions with fluoroxy compounds are CFiC 2O (RgSOzhO Suitable peroxides for use in the preparation of the compounds include SFsOOSFs CF300SF F luoroxy compounds which are useful in the inven- 'tion include oxygen difluoride (0 2), dioxygen difluoride (0 1 trioxygen difluoride (0 1 and the like.

The reactions of the acids, salts, anhydrides or peroxides with fluorine or with fluoroxy compounds are best carried out at temperatures of from -150 C. to about 100 C. Temperatures below about 30 C. are preferred. It will be understood that reactions are not carried out at temperatures at which a starting material or product is markedly unstable. Free-radical initiation methods such as heat, ultraviolet radiation, or microwave radiation are needed for the reactions. Rapid quench of the reaction products in cold traps is desirable in many cases. When both reagents are gaseous they may be mixed and allowed to react. When one reagent is solid, the gaseous reagent is passed slowly over the solid to bring about reaction. lnert solvents or liquid suspension media may be employed but are not necessary. The procedures employed are illustrated in the examples.

EXAMPLE 1 The sodium salt of trifluoroacetic acid is fluorinated by a static bed procedure in a brass rectangular-shaped box reactor having a sintered monel plate suspended across it. The vessel is equipped with a gas inlet tube below the sintered plate and a gas outlet tube and brass blow-out cap above it. A 2.1 g. sample of sodium trifluoroacetate (about 15.6 millimoles) is spread out on the sintered plate in the fluorinating vessel. The reactor is flushed with nitrogen, fluorine is introduced into the nitrogen stream, and the mixture is passed into the vessel. The effluent stream is passed through an iron tube containing sodium fluoride at room temperature to remove hydrogen fluoride (which is present in commercial fluorine) and then through a trap immersed in liquid air. A stream of about 4 percent (by volume) of fluorine in nitrogen is passed through the reactor at a flow rate of 0.01 cubic ft./min. for minutes, then a percent stream at a flow rate of 0.007 cubic ft./min. for 1 hour, and finally a 34 percent stream at a flow rate of 0.004 cubic ft./min. for 2 hours. During this 3% hour reaction period a total of 0.30 moles of fluorine is introduced into the reactor; the temperature inside the reactor varies from l7-22 C. The fluorine flow is discontinued and the reaction vessel is then purged with nitrogen for one-half hour. The residual material in the reactor is found to weigh about 0.6 g.; it consists principally of NaHF and NaF. An alternative method of preparing the peroxyfluorides is to introduce fluorine gas slowly into a pressure vessel containing either salts of oxalic acid or salts of perfluoroalkylcarboxylic acids.

The non-condensable gases are removed from the trap at liquid nitrogen temperature under reduced pressure. The liquid air trap is found to contain 9.3 millimoles of condensed products, including perfluoromethyl peroxyfluoride and perfluoroethyl peroxyfluoride. This material is isolated in pure form from the mixture by means of vapor phase chromatography. For this process a column 8 feet 7 inches in length and one-half inch in diameter packed with perfluorotributylamine (33 percent) coated on 30-60 mesh acidwashed filter aid(diatomaceous earth) (67 percent) and maintained at about 30 C. was used. An 8-volt thermistor was used as the detector. Helium was employed as the carrier gas at a flow rate of mL/min. The pure products are obtained by passing the stream from the chromatograph exit through cooled traps as the respective components elute. The component eluting with a retention time of approximately 350 relative to CF OF under identical chromatography conditions is trifluoromethyl peroxyfluoride.

The F nuclear magnetic resonance spectrum of trifluoromethyl peroxyfluoride contains two absorptions, one at --29 l .5 1b is due to the GOP group and the other at 69.2 41 due to the CF group. The 291.5 4: peak is split into a quartet by the CR group and the +69.2 peak is split into a doublet by the single F atom of the OOF group. The relative area ratio for the 69.2 peak to 29 l .5 do is 3: 1. The value of the coupling constant, J, is 4.5 cycles/sec.

The infrared spectrum of this material shows the following absorptions: 7.72p.(s), 7.90;;(s), 8.43p.(s), 10.6p.(m) and 13.l8;i(m). The relative intensities of the absorptions are indicated by the symbols S and M standing for strong and medium, respectively.

Elemental analysis of CF;, OOF gave the values 10.0 percent carbon and 61.8 percent fluorine. The molecular weight found was 122. Calculated for this compound are 10.0 percent carbon, 63.3 percent fluorine and a molecular weight of 120.

By irradiating a mixture of an excess of oxygen difluoride and FS(O )OOS(O )F, at room temperature with ultraviolet light, there is formed FS(O )OOF. The product, fluorosylfuryl peroxyfluoride, boils at about 0 C.

EXAMPLE 2 The compound CF CF OOF was also isolated from the products of the fluorination of salts of trifluoroacetic acid by vapor phase chromatography at 30 C. with perfluoroacetic acid by vapor phase chromatography at 30 C. with perfluorotributylamine as the stationary phase. The infrared spectrum of C F OOF shows strong similarities to the spectra of C F OF and CF OOF The F nuclear magnetic resonance spectrum of C F OOF shows an absorption at 29 l .6 d), assigned to the OOF group, at 84.1 d) (the CE, group), and at 97.4 d) (the CF group). The absorptions at 84.1 and 97.4 d) are consistent for CE, and C1 respectively, in a C 1 group adjacent to an oxygen atom as observed in CF CF OF (82.1 Q5 and 97.9 respectively). The relative area ratios of these absorptions are 113:2, respectively. The absorption of the COP group is split into a triplet by the CF group and a quadruplet by the CF group. The absorption of the CF group is split into a doublet by the single fluorine of the COP group and into a quadruplet by the CE, group. The absorption of the CF 3 group is split into a triplet by the CF and a doublet by the GOP, which are superimposed into a fourfold peak.

wherein Q is an atom in its highest oxidation state, said atom being selected from the classconsisting of carbon and phosphorus, R, is selected from the class consisting of fluorine and perfluoroalkyl radicals, m is 1-5 and n is zero to 2; and when Q is carbon and n is zero, R; is perfluoroalkyl and includes Q.

2. Trifluoromethyl peroxyfluoride having the form ula CF OOF.

3. Perfluoroethyl peroxyfluoride having the formula 

1. A COMPOUND OF THE FORMULA
 1. A compound of the formula wherein Q is an atom in its highest oxidation state, said atom being selected from the class consisting of carbon and phosphorus, Rf is selected from the class consisting of fluorine and perfluoroalkyl radicals, m is 1-5 and n is zero to 2; and when Q is carbon and n is zero, Rf is perfluoroalkyl and includes Q.
 2. Trifluoromethyl peroxyfluoride having the formula CF3OOF.
 3. Perfluoroethyl peroxyfluoride having the formula C2F5OOF. 